BREEDING BIOLOGY OF THE SIBERIAN TIT PARUS-CINCTUS IN FINLAND

The breeding biology of the Siberian Tit was studied in several areas within the whole breeding range of this species in Finland. A total of about 920 nests came to our knowledge The breeding densities exceeded 4 pairs/km(2) in best habitats and the population decline since the 1 940s has not been as marked as suspected. The onset of laying did not vary much between the study areas. The mean at Kuusamo (southern edge of the range) was 18 May, and 22 May at Kilpisjarvi where the environm ent is harshest. The mean clutch size was 7.94 with moderate geographi c variation, but no clear geographical trends. No genuine second clutc hes have ever been recorded in the Siberian Tit. The breeding success (number of young fledging of number of eggs laid) varied between 60 an d 87% being highest at Kuusamo and lowest at Kilpisjarvi.